EP0901257A2 - Verfahren zur Erzeugung eines Multimodulationsrahmens und zugehöriger Modulator - Google Patents

Verfahren zur Erzeugung eines Multimodulationsrahmens und zugehöriger Modulator Download PDF

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Publication number
EP0901257A2
EP0901257A2 EP98402023A EP98402023A EP0901257A2 EP 0901257 A2 EP0901257 A2 EP 0901257A2 EP 98402023 A EP98402023 A EP 98402023A EP 98402023 A EP98402023 A EP 98402023A EP 0901257 A2 EP0901257 A2 EP 0901257A2
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EP
European Patent Office
Prior art keywords
modulation
coefficients
filter
modulator
frame
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP98402023A
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English (en)
French (fr)
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EP0901257A3 (de
EP0901257B1 (de
Inventor
Gregorio Nunez Leon De Santos
Alfonso Fernandez Duran
Francisco Javier Casajus Quiros
José Manuel Peaz Borrallo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alcatel Lucent SAS
Original Assignee
Alcatel CIT SA
Alcatel SA
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Publication of EP0901257A3 publication Critical patent/EP0901257A3/de
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0008—Modulated-carrier systems arrangements for allowing a transmitter or receiver to use more than one type of modulation

Definitions

  • the present invention refers to a method for generating a multi-modulation frame, as well as to a modulator to implement the method.
  • the modulator according to the invention can, for example, be implemented in a unit of a mobile radiocommunications system.
  • a frame is defined as a signal which includes successive time intervals.
  • a multi-modulation frame is characterised in that it includes at least two time intervals 1 and 2, each being defined by their respective modulations which are different one from the other.
  • a frame of the type defined above can be employed for example in the DECT (Digital Enhanced Cordless Telecommunications) standard issued by the ETSI (European Telecommunications Standards Institute) with the objective of increasing the traffic capacity in at least one channel, or time interval, without changing the modulation defined for other channels and maintaining compatibility with other units of the same system which do not have the modulation changing facility.
  • DECT Digital Enhanced Cordless Telecommunications
  • ETSI European Telecommunications Standards Institute
  • a first time interval 1 is defined by a GFSK (Gaussian Frequency Shift Keying) modulation already used in the DECT standard and a second time interval 2 is defined by a modulation ⁇ /4DQPSK ( ⁇ /4-Differential Quadrature Phase Shift Keying).
  • the two modulations define respective constellations which are shown in figures 2A and 2B with respect to predefined reference axes.
  • the modulated signal is delimited by a spectral mask, the modulated signal having to be contained within this mask.
  • the resulting signal can, on one hand, produce a spectrum which does not lie within the delimited spectral mask and, on the other one, include intersymbol interferences which provoke the loss of symbols which coincide in time with the modulation change.
  • a first objective of the present invention is to provide a method for generating a multi-modulation frame which defines a spectrum that is contained within an amplitude-delimited spectral mask and suppresses intersymbol interferences.
  • a second objective of the invention is to define a modulator to implement the method defined by this invention.
  • a method for generating a multi-modulation frame which includes at least a first time interval and a second time interval, said first and second time intervals being defined by first and second modulations, respectively, is characterised in that said method comprises a step-by-step interchange stage, with at least two steps, for changing the coefficients of a modulation filter from a first set of coefficients associated with the first modulation to a second set of coefficients associated with the second modulation.
  • step-by-step coefficient interchange stage is realized by means of successive partial changes in the coefficients, changing in each step a few coefficients in the first set of coefficients associated with the first modulation for coefficients of the second set associated with the second modulation.
  • the first modulation is a GFSK modulation and the second modulation is a ⁇ /4DQPSK modulation.
  • a modulator to implement the method according to the invention comprises modulation filter means and means to effect, step by step, the change-over of the coefficients of said modulation filter means from the first set of filter coefficients associated with the first modulation to the second set of filter coefficients associated with the second modulation.
  • the method according to the invention avoids the transient effects produced by the change in modulation like intersymbol interferences or phase discontinuities, which appear in each of the successive frames when the change in modulation is applied without any adjustment mechanism at the instant which, with reference to figure 1, separates the two time intervals 1 and 2 .
  • a modulator comprises a first multiplier 10, a delay line 11 , a second multiplier 12 , an oversampler 13 , a configurable filter 14 and a digital-to-analogue converter 15 .
  • the binary signal bn is applied to a first input of the multiplier 10 the output of which is applied, on one hand, to a second input of the multiplier 10 through the delay line 11 and, on the other hand, to an input of the multiplier 12 .
  • This multiplier 12 receives, through a second input, the signal e j( ⁇ /M)n , where n is a bit rank.
  • the output of the multiplier 12 is connected to an input of the configurable filter 14 through the oversampler 13 .
  • the output of the configurable filter 14 is connected to an input of the digital-to-analogue converter 15 .
  • the modulator of figure 3 is also suitable for performing both GMSK modulation and ⁇ /4DQPSK modulation under the following conditions:
  • the Gaussian filter employed for the GMSK modulation intentionally introduces intersymbol interferences between the transient symbols.
  • a method to generate a multi-modulation frame which includes at least a first time interval 1 defined by a first modulation and a second time interval 2 defined by a second modulation, comprises a step-by-step interchange stage, with at least two steps, for changing the coefficients of the configurable modulation filter 14 from a first set of coefficients associated with the GMSK modulation to a second set of coefficients associated with the ⁇ /4DQPSK modulation.
  • the table on the following page shows more precisely an example of a step-by-step interchange stage for changing the coefficients of the configurable modulation filter 14.
  • Gaussian and root raised cosine filters employed for GMSK and ⁇ /4DQPSK modulations use the same number of coefficients, for example twelve (12) in the implementation described. This number of coefficients corresponds to the greatest number required by each of the filter types, Guassian and root raised cosine. As is shown in this table:
  • the step-by-step coefficient change is realized by means of successive partial changes in the coefficients, changing in each step a few coefficients of the first set of coefficients associated with the first modulation for coefficients of the second set of coefficients associated with the second modulation.
  • a step-by-step interchange stage can be designed for the coefficients of the configurable modulation filter 14 from coefficients associated with ⁇ /4DQPSK modulation to coefficients associated with GMSK modulation, when the transition takes place from ⁇ /4DQPSK to GMSK modulation.
  • this stage does not seem to have the same importance because the problem arises from the use of the Gaussian filter employed for GMSK modulation which introduces "tails" that interfere with the ⁇ /4DQPSK modulation symbols.
  • the configurable filter 14 comprises a modulation filter 140 , a synchronisation circuit 141 and a programming circuit 142.
  • the synchronisation circuit 141 receives the bit stream bn and, depending on predefined bits, for example synchronisation bits in the received frame, defines the frame synchronisation and, consequently, the modulation change-over time can be known.
  • the synchronisation circuit 141 actuates the programming circuit 142 , which, step-by-step, loads the coefficients COEF of the modulation filter 140 as is shown in the table above.
  • a demodulator to demodulate a multi-modulation frame produced by a modulator as the described with reference to figure 3 is shown in figure 4.
  • the demodulator comprises a root raised cosine filter 20 , a subsampler 21 and a first multiplier 22 connected in cascade.
  • the first multiplier 22 receives the signal e -j( ⁇ /M)n through another input.
  • the output from the first multiplier 22 can be connected to two branches shown in parallel.
  • a first branch, used to generate a differential output, comprises a second multiplier 24, a delay line 23 and a threshold detector 25 .
  • the second multiplier 24 receives at a first input the output signal from the first multiplier 22 and at a second input this same output signal from the first multiplier 22 delayed through the delay line 23 .
  • the output of the second multiplier 24 is applied to an input of a threshold detector 25 .
  • a second branch used to generate a coherent output, comprises a threshold detector 26 and a decoder 27 connected in cascade.
  • the demodulator can include a step-by-step interchange stage for the coefficients of the demodulation filter from a first set of coefficients associated with the GMSK modulation to a second set of coefficients associated with the ⁇ /4DQPSK modulation, this being done in correspondence with the change in coefficients in the modulator as was described above.
  • the demodulator comprises a configurable demodulation filter and a circuit for changing, step-by-step, the coefficients of this demodulation filter from a first set of coefficients adapted to the waveform of the first modulation to a second set of coefficients adapted to the waveform of the second modulation, and this being done in correspondence with the change of coefficients in the modulator.
  • This modulator must also include a frame synchronisation circuit to detect the modulation change time and, in consequence, activate the coefficient interchange circuit.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Time-Division Multiplex Systems (AREA)
EP19980402023 1997-09-02 1998-08-10 Verfahren zur Erzeugung eines Multimodulationsrahmens und zugehöriger Modulator Expired - Lifetime EP0901257B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ES9701873 1997-09-02
ES9701873 1997-09-02

Publications (3)

Publication Number Publication Date
EP0901257A2 true EP0901257A2 (de) 1999-03-10
EP0901257A3 EP0901257A3 (de) 2003-01-15
EP0901257B1 EP0901257B1 (de) 2004-12-01

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EP19980402023 Expired - Lifetime EP0901257B1 (de) 1997-09-02 1998-08-10 Verfahren zur Erzeugung eines Multimodulationsrahmens und zugehöriger Modulator

Country Status (6)

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EP (1) EP0901257B1 (de)
JP (1) JPH11146024A (de)
CN (1) CN1212546A (de)
AU (1) AU740096B2 (de)
CA (1) CA2242935A1 (de)
DE (1) DE69827885T2 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003056768A1 (en) * 2001-12-31 2003-07-10 Nokia Corporation Modulation-dependant transport channel configuration
EP2299599A1 (de) * 2004-09-21 2011-03-23 Kabushiki Kaisha Kenwood Drahtlose Kommunikationssteuervorrichtung und drahtloses Kommunikationsverfahren

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004052897B4 (de) * 2004-11-02 2017-03-30 Intel Deutschland Gmbh Funkempfänger und Verfahren für den Empfang von mit zwei Modulationsarten modulierten Datenbursts
JP4342565B2 (ja) * 2007-03-08 2009-10-14 株式会社東芝 送信機および受信機
WO2014094064A1 (en) * 2012-12-20 2014-06-26 University Of South Australia Digital communication system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996035274A1 (en) * 1995-05-01 1996-11-07 Motorola Inc. Method and apparatus for providing control and message channels

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2947770A1 (de) * 1979-11-27 1981-07-23 Siemens AG, 1000 Berlin und 8000 München Zeitmultiplexsystem
JPH0787154A (ja) * 1993-09-17 1995-03-31 Idou Tsushin Syst Kaihatsu Kk 多値直交振幅変調方式のフレーム同期方法
AU6804298A (en) * 1997-05-29 1998-12-03 Alcatel A multi-modulation frame for a radio communication system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996035274A1 (en) * 1995-05-01 1996-11-07 Motorola Inc. Method and apparatus for providing control and message channels

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
MORINAGA N ET AL: "INTELLIGENT RADIO COMMUNICATION TECHNIQUES FOR ADVANCED WIRELESS COMMUNICATIONS SYSTEMS" , IEICE TRANSACTIONS ON COMMUNICATIONS, INSTITUTE OF ELECTRONICS INFORMATION AND COMM. ENG. TOKYO, JP, VOL. E79-B, NR. 3, PAGE(S) 214-221 XP000588442 ISSN: 0916-8516 * abstract * Section 1 Section 2 *
POKLEMBA J J: "Digital tracking loops for a programmable digital modem" , MILITARY COMMUNICATIONS CONFERENCE, 1992. MILCOM '92, CONFERENCE RECORD. COMMUNICATIONS - FUSING COMMAND, CONTROL AND INTELLIGENCE., IEEE SAN DIEGO, CA, USA 11-14 OCT. 1992, NEW YORK, NY, USA,IEEE, US, PAGE(S) 644-650 XP010060940 ISBN: 0-7803-0585-X * abstract * Section Pre-Averager Receive Data Filter * figure 1 * *
SAMPEI S ET AL: "ADAPTIVE MODULATION/TDMA SCHEME FOR PERSONAL MULTI-MEDIA COMMUNICATION SYSTEMS" , PROCEEDINGS OF THE GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM). SAN FRANCISCO, NOV. 28 - DEC. 2, 1994, NEW YORK, IEEE, US, VOL. VOL. 2, PAGE(S) 989-993 XP000488685 ISBN: 0-7803-1821-8 * the whole document * *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003056768A1 (en) * 2001-12-31 2003-07-10 Nokia Corporation Modulation-dependant transport channel configuration
EP2299599A1 (de) * 2004-09-21 2011-03-23 Kabushiki Kaisha Kenwood Drahtlose Kommunikationssteuervorrichtung und drahtloses Kommunikationsverfahren

Also Published As

Publication number Publication date
DE69827885T2 (de) 2005-12-01
EP0901257A3 (de) 2003-01-15
CA2242935A1 (en) 1999-03-02
JPH11146024A (ja) 1999-05-28
EP0901257B1 (de) 2004-12-01
CN1212546A (zh) 1999-03-31
AU740096B2 (en) 2001-11-01
AU8191498A (en) 1999-03-18
DE69827885D1 (de) 2005-01-05

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